METHOD AND MOBILE TERMINAL FOR QUANTITATIVE MEASUREMENT BY CHROMATOGRAPHY OF AN ANALYTE OF INTEREST

Abstract

The invention relates to a method (200) for the quantitative measurement of an analyte of interest by chromatography, designed to be implemented by a mobile terminal. Such a method (200) comprises a step (210) of acquiring a stream of digital representations (20i) of a reactive strip delivered by the image sensor (22) and of selecting on the fly one of said digital representations (20i) as soon as it satisfies a set of predetermined relevance criteria. The method (200) further comprises a step (230) of producing a color intensity (I15i, I15', I15'') for each color profile (15i) expressed in a distribution of color intensities (100) obtained from the selected digital representation (20s'). The process (200) finally includes a step (240) of producing a measurement (M) of an analyte of interest from the respective color intensities (I15', I15'') of two color profiles (15i).Figure to be published with the abbreviation: Fig 3.

Description

Title of the invention: METHOD AND MOBILE TERMINAL FOR QUANTITATIVE MEASUREMENT BY CHROMATOGRAPHY OF AN ANALYTE OF INTEREST Technical field

[0001] The present invention relates to methods and systems for quantitative measurement of analytes of interest by chromatography, said analytes being contained in liquid biological samples.

[0002] The term "analyte" means any substance, constituent, or biological, chemical, or biochemical entity whose presence in a liquid biological sample is to be quantified. This analyte is, for example, an antibody, hormone, protein, peptide, enzyme, nucleic acid, or a specific element (e.g., antigen or epitope) of an infectious agent such as a virus or bacterium. The liquid biological sample in which the analyte may be in solution or suspension includes any biological or bodily fluid of a human or animal subject, such as blood, plasma, serum, saliva, sweat, tears, cerebrospinal fluid, or urine. Previous technique

[0003] The quantitative determination by chromatography of an analyte of interest contained in a liquid biological sample currently relies on the use of a reagent strip containing a detection or capture reagent adapted to the discrimination of said analyte of interest. This discrimination is manifested by a measurable color or fluorescence in a predefined detection zone, also called the "reactive zone," of the reagent strip. Parameters of this color, such as its intensity and / or extent, for example, allow for the quantitative measurement of the presence of the analyte of interest in the liquid biological sample.

[0004] The discrimination of an analyte of interest by an inhomogeneous distribution of color intensities in the detection zone most often takes the form of identifying color profiles associated with the chromatography technique used, such as a control line and a result line of the chromatographic test. In particular, the quantification of the analyte sought is most often directly related to the color intensity of the detected color profile(s). For example, the concentration of an analyte sought is generally proportional to the color intensity of the corresponding color profile. hereinafter referred to as "color profile intensity". Thus, a high color intensity is synonymous with a high concentration of molecules of interest.

[0005] In this regard, prior art exists for reading devices specifically designed to precisely determine the intensity of a color profile. Such a reading device is equipped with a receptacle that constrains a specific relative positioning (in terms of orientation, inclination, etc.) of a test strip with respect to image capture means also integrated into said reading device. The image capture conditions of said strip are thus fully controlled and predefined by the reading device, in order to prevent the presence of shadows or parasitic artifacts that could make chromatographic analysis of the strip impossible or compromise the relevance of such an analysis. To this end, known reading devices also incorporate their own specific lighting means to illuminate the reactive strip being measured within the receptacle with precision and homogeneity.

[0006] The combined arrangement of the reagent strip receptacle, the capture means, and the lighting means during image capture may, however, depend on the type of reagent strip to be analyzed. To accommodate this variety of reagent strips, it is known to use reading devices dedicated to specific types of reagent strips or, alternatively or in addition, to equip the reading devices with a wide range of parameters, the calibration of which requires a specialized operator to adapt the functionalities of said reading devices to each type of reagent strip to be analyzed. Thanks to this customization of the reading devices, the reagent strip analysis processes they implement are simplified because they lack the functions for controlling the quality of the image capture, which is by definition optimal, and for correcting captured images.These images are, by their very nature, free of noise, interference, and distortion thanks to the design and specialization of the reading devices. However, such processes are unsuitable and inappropriate for use with images captured outside of such a controlled capture environment.

[0007] Such chromatographic analyses using dedicated equipment are expensive due to the cost of designing, manufacturing, selling, and maintaining the reading devices, which require regular calibration, and remain the domain of specialist professionals. However, there is a need for widespread use of this type of analysis, whether at a patient's bedside, in the field, or at home.

[0008] Part of the journey towards facilitating the performance of biological tests in the field and making them accessible to all has been accomplished by the design of a microfluidic device for obtaining a plasma-reagent mixture, as disclosed in document FR3133922. Such a device 100 mainly comprises: - a blood collection module; - a passive and non-forced plasma separation module from the collected blood, preventing any risk of hemolysis or the use of sophisticated third-party devices such as a centrifuge; - a homogeneous mixing module for said plasma and a reagent; - an output module for such a mixture to be deposited onto a strip analysis.

[0009] Such a device clearly simplifies the process of collecting plasma and preparing a plasma-reagent mixture ready to be applied to test strips in the field, without requiring professionals or laboratory equipment. However, the need to transport such strips to a laboratory after application of the homogeneous mixture, when precise analysis and interpretation of results by operators specializing in dedicated reading devices is desired, undermines this objective of democratization.

[0010] Consequently, there is a need for methods and systems for the quantitative measurement by chromatography of an analyte of interest, without the need to use laboratory material or human resources while maintaining high reliability of results. Description of the invention

[0011] The invention proposes a method for the quantitative measurement by chromatography of an analyte of interest, said method being designed to be implemented by a processing unit of a terminal comprising an image sensor and an output human-machine interface, said method comprising: - a step of producing a color intensity for each color profile expressed in a digital representation of a development area of ​​a reactive strip; - a step of producing a measurement of an analyte of interest from the respective color intensities of two color profiles expressed in said digital representation of the development zone of said reagent strip.

[0012] To use a "consumer" electronic device such as a mobile terminal and avoid the need for a dedicated, expensive terminal reserved for professional use in laboratories, such a process involves: - a step of acquiring a stream of digital representations of the reactive strip delivered by the image sensor and of selecting on the fly one of said digital representations as soon as it satisfies a set of predetermined relevance criteria; - a step of developing a working image from said selected digital representation, said working image describing a distribution of colour intensities of said development area of ​​said reactive strip.

[0013] Furthermore, such a method is designed so that the digital representation of a development area of ​​a reactive strip used by the production step of a color intensity for each color profile consists of the working image, said production step being arranged to, from said distribution of color intensities expressed by said working image: - identify each color profile; - calculate the intensity of the colour of the latter.

[0014] Finally, the step of producing a measurement of an analyte of interest by such a process according to the invention: - consists of calculating a ratio between the respective color intensities of two color profiles; - causes an output of said measurement of an analyte of interest produced by the output human-machine interface of the mobile terminal.

[0015] To maximize the relevance of the captured digital representations and automatically trigger the measurement process of the analyte of interest as soon as possible, the step of acquiring a stream of digital representations of the reactive strip delivered by the image sensor and selecting, on the fly, one of said digital representations may include: - a sub-step of capturing a digital representation; - a sub-step of searching within said digital representation for the outline of an inner surface of a reactive strip including a development zone, and of selecting said digital representation: • if a surface contour describing the outline of a predefined geometric shape of a reactive strip surface has been identified, and • if a ratio between Faire captured by such a surface contour and the total area of ​​said digital representation is greater than and at a predetermined threshold.

[0016] To guide the terminal user in correctly positioning the terminal relative to the reactive strip during the acquisition of a stream of digital representations, said terminal advantageously being a mobile terminal, the acquisition of a stream of digital representations of the reactive strip delivered by the image sensor and the on-the-fly selection of one of said digital representations may include a sub-step of displaying it via the interface output human-machine interface of the terminal such that a suitable geometric shape describing a typical template of a "control" reactive strip is transparently superimposed on said digital representation in order to prompt the terminal user in positioning its image sensor relative to the reactive strip so that said suitable geometric shape covers the visible surface of the reactive strip on said digital representation displayed by said output human-machine interface.

[0017] To compensate for suboptimal image acquisition conditions due to the free positioning of the terminal's image sensor, the latter advantageously being a "consumer" mobile terminal, the step of developing a working image from said selected digital representation may include: - a sub-step of working image production consisting of: • a discrimination of pixels describing a region of interest within the selected digital representation, said region of interest expressing the area of ​​revelation; • a production of said working image comprising pixels expressing the respective light intensities of the pixels expressing the area of ​​revelation in the selected digital representation; - a sub-step of correcting geometric distortions in the selected digital representation or in the working image produced with regard to an expected and predefined shape of a typical development area of ​​a reactive strip.

[0018] According to an advantageous embodiment, the step of producing a color intensity for each color profile may include: - a sub-step of modeling the distribution of colour intensities expressed in the working image in the form of a colour intensity curve describing the cumulative colour intensity by each set of pixels aligned perpendicularly to a longitudinal axis of the reveal area; - a sub-step of identifying a color profile from said color intensity curve and determining a range of abscissas characterizing the beginning and end of said color profile; - a sub-step of calculating the color intensity of said color profile identified as being the area under the intensity curve over said determined abscissa range.

[0019] To analyze the entire detection area of ​​a reagent strip, an instance of such a substep of identifying a color profile from said color intensity curve and determination of a range of abscissas characterizing the beginning and end of said color profile, as well as an instance of such a substep of calculating the color intensity of said identified color profile, may be iterated from the lowest abscissa to the highest abscissa of said color intensity curve.

[0020] In order to reduce the negative impact induced by the presence of a residual colour intensity resulting from less than optimal lighting conditions of the reactive strip during the acquisition step, the substep of calculating the colour intensity of said identified colour profile may include a step of subtracting an area of ​​residual colour intensities from the area under the intensity curve on said determined abscissa range characterizing a colour profile.

[0021] In this case, said substep of calculating the color intensity of said color profile can be arranged so that the area of ​​residual color intensities of a color profile consists of the area under a curve defined by an affine function linking the beginning and end of the color profile on said range of abscissas characterizing said color profile on the intensity curve.

[0022] According to a second object, the invention relates to a computer program product comprising program instructions, which, when written into a program memory of a terminal further comprising a processing unit, an output human-machine interface and a data memory, and interpreted or executed by said processing unit of the latter, cause the implementation of a method for quantitative measurement by chromatography of an analyte of interest according to the invention.

[0023] According to a second object, the invention relates to a mobile terminal comprising a program memory, a processing unit, an output human-machine interface and a data memory, the program memory of which contains the program instructions of such a computer program product. Brief description of the drawings

[0024] The invention will be better understood and other features and advantages thereof will become apparent from the following description of particular embodiments of the invention, given by way of illustrative and non-limiting examples, and with reference to the accompanying drawings, among which:

[0025] [Fig-1] schematically illustrates an implementation of a measurement method quantitative chromatography of an analyte of interest likely to be contained in a liquid biological sample received by a reagent strip according to various embodiments;

[0026] [Fig.2] schematically illustrates modules or functional elements of a mobile terminal enabling the implementation of the aforementioned process according to various embodiments;

[0027] [Fig.3] schematically presents functional steps of a measurement process quantitatively as described above according to various modes of implementation;

[0028] [Fig.4] illustrates through a graphical representation of a distribution color intensities of a development zone of a reactive strip, the implementation of a color profile detection step and production of a color intensity for each of the color profiles;

[0029] [Fig.5] illustrates through a graphical representation of a distribution color intensities of a development zone of a reactive strip, the implementation of a variant of realization of such a step of detection of color profiles and production of a color intensity for each of the color profiles, in order to get rid of residual color intensities. Description of the implementation methods

[0030] In order to simplify the description of the different embodiments which will be represented in the remainder of this description, the same references will be used on the different figures to designate the same elements or similar elements which are interchangeable with each other.

[0031] The [Fig.1] presents a reactive strip 1, in particular an immunochromatographic strip, comprising an outline 11 of an inner surface 12 of said reactive strip 1.

[0032] The peripheral contour 11 may be rectangular, rounded rectangular, ellipsoidal, generally rectangular with gripping notches, or, more generally, elongated. In one embodiment, this contour 11 is the peripheral edge of the reactive strip 1, in other words, the edge defining its shape.

[0033] In another embodiment, the contour 11 is a trace that surrounds said inner surface 12 by following the outer peripheral edge of the reactive strip 1. This trace can mark the perimeter of the reactive strip 1 or be printed, embossed, woven or, more generally, marked in any other equivalent way on the surface of the reactive strip 1.

[0034] The inner surface 12 of the test strip 1 is designed to receive a liquid biological sample. This liquid biological sample can, in fact, be deposited in a predefined deposition zone of the test strip 1 and migrate along it by capillary diffusion. For example, the test strip 1 is a lateral flow immunoassay, also known by the acronym "LFI" of (the Anglo-Saxon expression "Lateral Flow Immunoassay"). Alternatively, the test strip 1 can be immersed in the liquid biological sample. The test strip 1 is, in fact, designed in a known manner to receive the liquid biological sample and to discriminate the possible presence of the analyte of interest by means of an inhomogeneous distribution of color intensities of the material forming said detection zone (13).

[0035] The inner surface 12 of the test strip 1 includes at least one detection zone 13 for revealing the presence of an analyte of interest in a liquid biological sample received by the test strip 1. The detection zone 13 is designed to allow visual identification of an analyte of interest that may be contained in the liquid biological sample received by the test strip 1. To this end, the test strip 1 includes a specific detection or capture reagent that enables the analyte contained in said liquid sample to be revealed in the detection zone 13. Alternatively or in addition, such a reagent may be present in the biological sample, through premixing, as proposed in document FR3133922.

[0036] A test strip may optionally comprise a plurality of detection zones 13 for the detection of a plurality of analytes of interest. Thus, depending on its structure, a test strip 1 allows the determination of a single analyte (mono-analyte) or the determination of a plurality of analytes of interest.

[0037] In a non-limiting embodiment, the inner surface 12 of a test strip 1 comprises a chromatographic test identifier 14. This identifier may be in graphic form, for example, as a barcode or QR code label (or "tag"). This identifier is, for example, associated with the analyte being sought and / or allows for tracking of the test strip 1 for improved results management.

[0038] In a non-limiting embodiment, the chromatographic test identifier 14 incorporates or is associated with position (or location) data within the inner surface 12 of the detection zone 13. The location of the detection zone 13 within the test strip 1 may, in fact, vary from one type of chromatographic test to another or from one brand of test strip 1 to another.

[0039] Unlike a dedicated reading device known in the prior art, the invention proposes to be able to use so-called "consumer-grade" equipment, for example in the advantageous form of a suitable smartphone 2, by implementing a mobile application designed for this purpose, to perform a quantitative measurement of an analyte of interest in a liquid biological sample received by the test strip 1. Such equipment 2 may, instead of or in addition to a mobile phone, be a digital tablet, a computer or, more generally, a device or mobile terminal implementing a reading method according to the invention. It is sufficient that said equipment 2 has means for capturing the reactive strip 1 and / or for analyzing images of said strip 1 produced by a third-party device.

[0040] Referring to [Fig. 2], a terminal 2 comprises a processing unit 21 including one or more microprocessors, microcontrollers arranged to implement one or more computer programs. Said processing unit 21 controls, by means of signals carried by a communication bus symbolized in [Fig. 2] by double arrows in single lines, electronic elements including a memory M. The latter comprises a data memory 24 and a program memory 23, said memories 23 and 24 being able to form a single physical entity M.

[0041] The term "memory" refers to any computer memory, whether volatile or non-volatile. Non-volatile memory is computer memory whose technology retains its data in the absence of an electrical power supply. It can contain data resulting from input, calculations, measurements, and / or program instructions. The main non-volatile memories currently available are electrically writable, such as EPROM (Erasable Programmable Read-Only Memory), or electrically writable and erasable, such as EEPROM (Electrically Erasable Programmable Read-Only Memory), flash, SSD (Solid-State Drive), etc. Non-volatile memories are distinguished from so-called "volatile" memories, whose data is lost in the absence of an electrical power supply.The main volatile memories currently available utilize RAM (Random Access Memory, also known as "Random Access Memory"), DRAM (dynamic random access memory, requiring regular updating), SRAM (static random access memory requiring such updating during power under-power conditions), DPRAM or VRAM (particularly suited to video), etc.

[0042] According to [Fig. 2], a terminal 2 further comprises means of communication 26 with the outside world in the form of an input unit and an output unit. Thus, the terminal 2 can communicate with an application server 3 or a remote computer system 3. Said means of communication 26 cooperate with the processing unit 21 and ensure wireless or wired proximity communication with any other remote electronic entity 3.

[0043] To operate, a terminal 2 generally includes an electrical power source 27, external or internal in the form of one or more batteries, for example. The processing unit 21 may also include control means of an input and / or output human-machine interface 25. An "output human-machine interface" is defined as any device, used alone or in combination, that outputs or delivers a graphical, haptic, auditory, or, more generally, human-perceptible representation. Such an output human-machine interface may consist, but is not limited to, one or more screens, speakers, or other suitable alternative means. An "input human-machine interface" is defined as a computer keyboard, a pointing device, a touchscreen, a microphone, or, more generally, any interface designed to translate a gesture or instruction issued by a human into control or parameter data. Advantageously, the input and output human-machine interfaces may constitute a single physical entity, for example, when said terminal 2 consists of a smartphone.

[0044] The operation of terminal 2 can be adapted by loading into its program memory 23 a computer program P containing instructions arranged to trigger, when executed by the processing unit 21, the implementation of a suitable process. This program can use any programming language and be in the form of source code, object code, or code intermediate between source and object code, such as in an interpreted, partially or fully compiled form, or in any other desirable form.

[0045] A terminal 2 includes an image sensor 22 enabling the acquisition of a stream of digital images 20 from the reactive strip 1. The image sensor 21 is, in particular, a camera capable of providing a stream of video images by series of matrix digital representations (better known by the English term "frames") at a predefined frequency, prior to a possible recording of all or part of these frames in the form of matrix digital images in data memory 24.

[0046] A "digital image" or "frame" is understood to be a set of pixels capable of being displayed on a display screen, such as the screen 25 of terminal 2. Each pixel can be defined by at least one parameter, such as a color and / or a light intensity level. A digital image is advantageously in the form of a computer image file, for example, in raster mode, vector mode, or pixel mode, the content of which can be processed by the processing unit 21 of terminal 2. Thus, the program instructions of a computer program P, when executed by said processing unit 21, allow the operation of terminal 2 to be adapted so that it processes digital representations 20 acquired by the image sensor 22 and determines a result of the chromatographic test, in the same way as a dedicated reading device according to Article 10 of the French Intellectual Property Code. prior. Advantageously, the processing unit 21 is configured to perform on-the-fly (i.e., real-time or dynamic) processing of the captured frames 20 without interrupting the image acquisition procedure of the reagent strip 1 and without requiring the storage in data memory 24 of a plurality of images resulting from the acquisition procedure. Indeed, a method 200 (detailed later in connection with [Fig. 3]) for the quantitative measurement by chromatography of an analyte of interest according to the invention may include on-the-fly selection of a frame if it satisfies one or more necessary and sufficient criteria to perform a relevant analyte measurement.The invention thus allows a non-professional user to use consumer-grade equipment, such as their smartphone 2, to capture a stream of images from a test strip 1 under various lighting conditions and relative positions of their device 2 with respect to the test strip 1. As soon as a satisfactory frame is selected by their device 2, the analyte measurement is initiated. Conversely, the device 2 prompts the user, via its output human-machine interface 25, to continue acquiring the image stream until such a frame is automatically selected by their device 2, so that said user U can orient and / or position their device 2 with respect to the test strip to modify the capture conditions and / or ambient lighting.The display screen 25 of terminal 2 thus allows visualization of the stream of digital images 20 being acquired by the image sensor 21 and / or content generated by the processing unit 21 to guide the user U in their image acquisition procedure.

[0047] Referring now to [Fig. 3], a method 200 for the quantitative measurement by chromatography of an analyte of interest implemented by the processing unit 21 of a mobile terminal 2 such as that illustrated by [Fig. 2], comprises, like a method implemented by a dedicated reading device according to the prior art: - a step 210 of image acquisition of a reactive strip 1; - a step 230 of production of a colour intensity I15i for each identified color profile 15i; - a step 240 of producing a measurement M of an analyte of interest from the respective color intensities 115', 115” of two identified color profiles 15' and 15”.

[0048] Such a method 200 according to the invention differs, however, from those known in the prior art in several respects. First, instead of an image acquisition step 210 consisting of capturing an image of the reactive strip under optimal capture conditions, the acquisition step 210 of a method 200 according to the invention consists of acquiring a stream of digital images 20 of such a reactive strip 1 and selecting a digital representation 20s of said reactive strip from said stream 20. Such a selection can advantageously be made on the fly by selecting a frame if the latter satisfies one or more predetermined relevance criteria.

[0049] Furthermore, taking into account the random conditions of captures, by a free image acquisition procedure via a general public equipment, a measurement method 200 according to the invention includes a step 220 of developing a working image 20s' from said digital representation selected 20s in step 210, working image 20s' which describes a development area 13 of said reactive strip 1 expressing a distribution of colour intensities.

[0050] Given the uncontrolled and suboptimal capture conditions, prior to the production 230 of a color intensity U5i for each color profile 15i expressed in said working image 20s', said production 230 consists of identifying such color profiles 15i by exploiting the color intensity distribution of said working image 20s'. The production of a color intensity U5i for an identified color profile 15i is also suitable.

[0051] Finally, step 140 of producing a measurement M of an analyte of interest from the respective unit color intensities 115', 115" of two identified color profiles 15' and 15" can be similar to those known in the prior art. However, thanks to the invention, such a measurement M is provided in real time to the user via the output human-machine interface 25 of the mobile terminal 2, which was also used for the free acquisition of images of the reactive strip 1.

[0052] A method 200 according to the invention therefore comprises a step 210 of acquiring a stream of digital images 20 of a reactive strip 1 by the image sensor 22 of the mobile terminal 2. Such a step 210 includes a first substep of capturing 201 of a frame, the display 202 of which by the human-machine interface 25 is triggered, preferably, concurrently with the capture 201 by the processing unit 21 of the terminal 2. To assist or guide the user U in acquiring images of a reactive strip 1, a suitable geometric shape to describe the typical template of a "control" strip can be superimposed transparently on the frames displayed by the output human-machine interface 25 during the capture of the frames to facilitate the gestures of the user U.According to this advantageous embodiment, the user U of the terminal 2 is guided and encouraged to correctly position their mobile terminal 2 relative to the reactive strip 1 so that the appropriate geometric shape covers the visible surface of the reactive strip 1. A positioning will be judged correct when the user naturally orients the image sensor 22 of their terminal 2 so that the reference template covers, or even aligns with, a visible surface of the reactive strip 1 on the displayed frame.

[0053] Step 210 comprises, in real time and on the fly, a substep 203 for selecting a frame 20i from the stream of digital representations 20 delivered by the image sensor 22. To be selected, such a current digital representation or frame 20i must satisfy one or more predefined relevance criteria for a subsequent implementation of an analyte measurement step 240. Such relevance criteria relate, non-exhaustively and by way of example, to capture conditions such as ambient brightness, sharpness, contrast, and color temperature of the captured image, as well as to the content it expresses. Such a content criterion relates, for example, to the geometry, shape, and dimensions of a captured object and / or the presence of a graphic label also present on such an object detected in the frame.

[0054] Thus, if a frame 20i is, for example, deemed too blurry, too dark, or conversely overexposed, or if its content exhibits excessive non-linear geometric distortion, or even if said frame 20i does not describe any shape resembling a reactive stripe (situation illustrated by link 203-3 in [Fig. 3]), the frame 20i is ignored and not selected. Step 203 examines the next frame within the stream 20. As soon as a frame 20i satisfies these relevance criteria (situation illustrated by link 203-y), it is selected, the acquisition step 210 ceases in favor of a step 220 for producing a working image from which an analyte measurement can be performed.

[0055] To detect the presence of a digital representation of a reactive strip 1 within a frame 20i, substep 203 may consist of a search for a contour of an interior surface 12 of said reactive strip 1 comprising a revealing area 13.

[0056] In one embodiment, said substep 203 can be arranged to search for a contour 11 of a predefined geometric shape of a reactive strip surface, for example, a substantially rectangular contour. In an advantageous embodiment, a Hough transformation can be applied to said detected contour 11 in order to create straight contour lines. Such a substep 203 can then consist of calculating a ratio between the area captured or delimited by such a detected surface contour and the total area of ​​said acquired digital representation 20i. A ratio that is too low (for example, less than 30%) or too high (greater than 90%) will be such as to reject the frame 20i, automatically considered to have been captured at a distance separating the reactive strip 1 from the capture means 22 of the terminal 2 that is unsuitable for producing a relevant digital representation of the reactive strip 1.Such a check advantageously prevents image acquisition 201 carried out at a shooting distance that is too great or too far. Weak reactive strip 1, synonymous with images of insufficient quality (noise, blur, excessive pixelation, etc.).

[0057] To detect a contour 11 of a test strip 1, substep 203 may consist of querying a database (stored, for example, in the data memory 24 of the terminal 2) describing properties and / or templates of a plurality of commercially available test strips. These properties may include the two-dimensional shape of a test strip viewed from above, said shape being rectangular, with rounded corners, ellipsoidal, having one or more notches or gripping shoulders, concave or convex portions, etc. Such properties may, alternatively or in addition, describe a ratio between two of the dimensions of a test strip or, more generally, any geometric property or distinctive feature (a symmetry, a color and / or a marking, for example) characteristic of a test strip among its peers.

[0058] Alternatively or in combination, such a substep 203 may exploit a pattern recognition algorithm, for example a machine learning technique, an artificial neural network, alone or in combination with a Hough transform, to detect such a contour 11 of a reactive strip representation within a frame 20i. Such a substep 203 may further consist of implementing a machine learning algorithm to compare the acquired digital frame 20i to reference images, etc. The invention is not limited to the aforementioned examples of techniques that can be used to select a relevant frame 20s.

[0059] Thus, substep 203 advantageously consists of an automatic selection of a frame 20s retained for the continuation of the implementation of process 200 or, in other words, an automatic pre-sorting of the frames 20i of the image acquisition stream 20.

[0060] According to an advantageous embodiment of a method 200 according to the invention, when no frame taken from the acquisition stream 20 can be selected because they all fail the relevance test carried out by substep 203, the latter can trigger the implementation of a substep 204 arranged to cause the output, via the output human-machine interface 25 of the terminal 2, of a help message or more generally, an invitation to the user suggesting to the latter a repositioning of the terminal 2 with respect to the reactive strip 1, a modification of the ambient lighting and / or a reconfiguration of the image sensor 22.

[0061] As mentioned previously, a method 200 according to the invention includes a step of developing a working image 20s' from a selected digital representation (frame) 20s describing a development area 13 of said reactive strip 1.

[0062] The purpose of such a working image is to express as accurately as possible the color intensity distribution 100 of a development area 13 of a reactive strip. This step 220 is crucial because the image acquisition procedure 210 is free and open to any user of "consumer-grade" equipment 2, such as a smartphone. Unlike state-of-the-art techniques using dedicated reading devices, the capture conditions cannot be optimal, although the selection 203 may have rejected any frame too far removed in terms of relevance for the subsequent implementation of the process 200.

[0063] Thus, the use of a "general public" mobile terminal 2 inevitably leads to the presence of imperfections in the selected frame 20s, such as shadows, artifacts, parallax effects resulting from capture incidents during the acquisition step 210. The step 220 therefore consists of correcting the selected image 20s to produce a working image 20s' suitable for conducting the subsequent analyte measurement step 240.

[0064] Following the selection step 210, the selected image or frame 20s comprises a graphic and digital representation of a strip 1. Step 220 then includes a substep 221 for extracting a region of interest within the image 20s, comprising the development area 13 of the reactive strip 1. A working image 20s' can be obtained after recentering said region of interest (mainly comprising the transcription of the development area 13) and cropping to remove the area outside said region of interest. Such a substep 221 can further consist of creating a grayscale working image 20s' encoding a light intensity per pixel.Advantageously, prior to such a grayscale conversion, the area of ​​interest can be deconvolved from the selected digital representation 20s, so that a dominant color best expresses the reveal area 13, particularly the color profiles 15, in relation to the rest of the image. Such a substep 221 can thus rely on the singular value decomposition technique, also known by the abbreviation SVD. This decomposition aims to better separate the signal of the color profiles 15 (for example, in blue or red) from the rest of the reveal area (generally white).

[0065] Such a substep 221 may further consist of the application of a known technique aimed at implementing elementary operations (dilations then erosions) to reduce noise in the working image 20s' obtained.

[0066] Step 220 may further include a substep 222 for correcting any possible distortion in the selected frame 20s or in the image 20s' from substep 221. Such distortion may result in a geometric deformation of the inner surface 12 of the captured digital representation of The strip 1, whose expected and predefined shape is generally rectangular, is often distorted by the captured inner surface 12, which has concave sides and / or elongated vertices, or is trapezoidal in shape. Several factors can cause distortion in an image 20s or 20s'. For example, approximate and free spatial positioning of the mobile terminal 2 relative to the reactive strip 1 can induce parallax errors. Similarly, the optics of the capture means 22 can also cause distortion (pincushion or fish-eye effect) of the digital representation of said strip 1 resulting from the capture step 210. This substep 222 can thus consist of correcting the somewhat distorted digital representation of the development area 13.Such a correction can be achieved by implementing a trained machine learning algorithm equipped with a database containing distortion-free images of reactive strips. This algorithm thus makes it possible to identify and correct any detected distortion in order to restore a digital representation that most closely reflects reality.

[0067] Thus, said substeps 221 and 222 are more generally arranged to detect and correct any geometric and / or colorimetric aberration presented by the image from the selected frame 20s and produce a working image 20s' describing in a relevant way a development zone 13 expressing one or more color profiles 15i, suitable for use by the rest of the process 200.

[0068] A method 200 for the quantitative measurement by chromatography of an analyte of interest implemented by the processing unit 21 of a mobile terminal 2 such as that illustrated in [Fig. 2], according to the invention, comprises a step 230 of producing a color intensity 115i, 115', 115” for each color profile 15i, 15', 15” expressed in a digital representation 20s' of said test strip 1, in this case within the working image 20s' produced previously in step 220. The implementation of such a step 230 can be iterated as many times as there are development zones 13 within said image 20s' or as many working images 20s' associated with each development zone 13 of a test strip, if the latter comprises several.

[0069] Advantageously, but not limitingly, a working image 20s' describes a development zone 13 in the form of a digital matrix representation, oriented such that any longitudinal axis of said development zone (generally in the form of a band) is horizontal. Thus, one or more color profiles 15 describe lines or bars of more or less homogeneous color oriented perpendicular to a longitudinal axis AL of the development zone 13. By convention, to illustrate the operation of a process 200 according to the invention, we will consider that the image 20s' produced in step 220 is such that The first color profile 15' revealed is a so-called "control profile," while a second color profile 15" reveals the presence of an analyte when traversing a development zone 13 from left to right along a transverse axis of said development zone AL. The number of color profiles 15 in a development zone 13 can be predefined by the user as a predetermined parameter or be determined by the chromatographic test type TI associated with the test strip 1 if said type is automatically identified. As described previously, this test strip 1 can be determined by any characteristic specific to it (shape, dimensions, chromatographic test identifier 14, color, QR code, dimensions, or position / orientation of the development zone 13 within the inner surface 12).Its TI type can thus be determined, in an optional substep 223, by means of a machine learning algorithm, said TI type serving as a configuration parameter for steps 230 and 240 of process 200.

[0070] In order to ultimately produce a measurement related to an analyte of interest, a method 200 according to the invention comprises a step 230 for producing a color intensity for each color profile identified in the working image 20s' representing the development zone 13 of the reagent strip. Such a step 230 comprises a substep 231 for modeling the color distribution expressed by said development zone 13 within a working image 20s' in the form of a color intensity curve 100. More specifically, such a substep 231 consists of translating said revealing area 13 into the form of a histogram of light intensities for which the amplitude of each histogram bar translates the sum of the light intensities of the pixels of the same column of the matrix image 20s' when traversing such an image 20s' from left to right along a longitudinal axis AL of the revealing area 13.Such an intensity histogram can also be expressed as a linear curve 100 whose ordinates describe cumulative color intensities for a column of pixels of the image 20s' and whose abscissas correspond to these same columns of pixels considered from left to right along such an axis AL of the development zone 13. We will subsequently refer to an "intensity curve" 100 to characterize the result of such a substep 23s of modeling the digital representation of a development zone 13 of a reactive strip 1, in this case the working image 20s'. Depending on the presence or absence of analytes, such an intensity curve 100 exhibits a plurality of slopes or peaks characterizing respectively one or more color profiles 15.

[0071] Thus, [Fig. 4] presents an example of such an intensity curve 100 produced in a substep 231 of a process 200 according to the invention. Such a curve Curve 100 describes a first profile 15' (control profile), strongly marked by the presence of one or two partially overlapping peaks, high light intensities (abscissas between 150 and 270), and a second color profile (measurement profile) 15” (abscissas between 450 and 550) of lower amplitude. Such a curve 100 illustrates the non-homogeneity of the color profiles 15 present in a development zone 13 of a reagent strip 1. Classically, a color profile is represented overall as a bell-shaped or Gaussian distribution whose mean is the center of said color profile and reflects the average intensity of said color profile, and whose standard deviation describes the width of said bell-shaped distribution.

[0072] The step 230 of producing a color intensity for each color profile 15 expressed in the working image 20s' expressing the development area 13 of the reactive strip, thus iteratively comprises, that is to say as long as (situation illustrated by link 234-n on the [Fig.3]) the working image 20s' reveals a color profile 15i, by traversing said image 20s' from left (low abscissas) to right (high abscissas), two instances of substeps 232 and 233, respectively of identification of said color profile 15i and of calculation of its color intensity U5i. Thus, according to the example illustrated by figures 3 and 4, two color profiles 15' and 15” were identified from the intensity curve 100 produced in substep 231. Each instance of a substep 232 is followed by an instance of a subsequent substep 233 of calculating the intensity I15i of each color profile 15i identified in 232.Such a calculation 233 of the intensity of a color profile 15 can consist, in a simplified way, of calculating Faire under the intensity curve 100 for the range of abscissas characterizing said color profile 15. Thus, on [Fig.4], the range of abscissas 15'ar characterizes a first color profile 15' and the range 15”ar characterizes a second color profile 15”. The number of iterations of substeps 232 and 233 can therefore vary from one reagent strip to another, that is to say according to the number of color profiles 15i that can express a development zone 13 of a reagent strip 1.

[0073] According to a first embodiment, substep 232 consists of fitting a Gaussian distribution (the 15'G Gaussian for the 15' color profile in [Fig. 4]) or a mixture of Gaussians (the set 15'Gm of the 15'G1 and 15'G2 Gaussians for the 15' color profile in [Fig. 4]) to the curve 100 for each color profile. Substep 233 then consists of calculating the integral of said fitted Gaussians. We can note in the example illustrated by [Fig. 4] that a 15' color profile can have a single maximum, in this case the 15'M maximum for the 15' profile, or several maxima, in this case two maxima, 15'Ma and 15'Mb, for the 15' profile. This peculiarity stems from the inhomogeneity of coloring of a coloring profile. Substep 232 considers the set of 15'GM Gaussians as defining a single profile because the respective means of the two Gaussians 15'G1 and 15'G2 of said set or mixture of Gaussians are not separated by a sufficient step (i.e., by a sufficiently wide range of abscissas) to characterize two distinct coloring profiles. The fact that said two Gaussians partially overlap corroborates this assumption.

[0074] Alternatively, a substep 232 aimed at identifying a color profile 15i may consist of detecting a range of abscissas that characterizes it, that is, detecting a "start" 15'b, 15"b and an "end" 15'e, 15"e, of a distribution substantially bell-shaped or a mixture of bells. For this purpose, such a substep 232 may implement a calculation of the gradient of the intensity curve 100. The calculated gradient advantageously makes it possible to find notable points such as local or global extrema (minimums or maxima), the average slope of the intensity curve 100, or the slope of said intensity curve 100 between two values ​​of interest. In particular with the calculated gradient, the maximum values ​​15'Ma, 15'Mb and 15”M allow us to identify the core or average of each 15', 15” color profile and / or the number of these 15 color profiles revealed.The minimum values ​​around these averages allow us to obtain an estimate of the abscissa ranges 15'ar and 15”ar representing respectively the said 15' and 15” colour profiles in the example of [Fig.4]. Substep 233 then consists of calculating, for each detected 15' and 15” colour profile, the area under the intensity curve 100 for each determined 15'ar and 15”ar abscissa range.

[0075] In connection with [Fig. 4], the invention provides a particularly advantageous embodiment for determining the beginning of a color profile, especially when it has a plurality of maxima, like the 15' color profile, and thus the lower bound of the abscissa range that characterizes it. According to the example illustrated by [Fig. 4], the first 15' color profile can be modeled from a mixture 15'GM of a first Gaussian 15'G1 and a second Gaussian 15'G2.

[0076] Thus, substep 232 may consist of: - to determine the lower bound of the 15'ar range characterizing the 15' color profile, the selection of an abscissa closest to that of a maximum between the mean of a first Gaussian distribution 15'G1 of the mixture of Gaussian distributions 15'GM and the lower bound of an interval defined by a predefined number of standard deviations (for example, three) of a second Gaussian distribution 15'G2 of said mixture of Gaussian distributions 15'GM centered around the mean of this second Gaussian distribution 15'G2, the mean of the first Gaussian distribution 15'G1 being the smallest mean among the means of the Gaussian distributions of said mixture 15'GM, the mean of the second Gaussian distribution 15'G2 being the second smallest mean among the means of the Gaussian distributions of said mixture 15'GM; - to determine the upper bound of the 15'ar range characterizing the 15' colour profile, the selection of a second abscissa close to the minimum between the mean of the Gaussian distribution 15'G2 of said mixture 15'GM and the upper bound of an interval defined by a predefined number of standard deviations (for example, three) of the first Gaussian distribution 15'G1 of said mixture 15'GM centered around the mean of this first Gaussian distribution 15'G1, the mean of the Gaussian distribution 15'G2 being greater than the mean of the Gaussian distribution 15'G1, the mean of the Gaussian distribution 15'G2 being the second smallest mean among the means of the Gaussian distributions of said mixture 15'GM having a height less than a first predefined threshold value.

[0077] More generally, to determine the upper bound of such a range of abscissas 15'ra characterizing a color profile modelable by a mixture 15'GM of Gaussian distributions having a number n greater than or equal to two, such a substep 232 may consist of selecting an abscissa close to the minimum between the mean of the Gaussian distribution 15'Gn of said mixture 15'GM and the upper bound of an interval defined by a predefined number of standard deviations (for example, three) of the Gaussian distribution 15'Gn-1 of said mixture 15'GM centered around the mean of this Gaussian distribution 15'Gn-1, the mean of the Gaussian distribution 15'Gn being greater than the mean of the Gaussian distribution 15'Gn-1, the mean of the Gaussian distribution 15'Gn being the second smallest mean among the means of the distributions Gaussians of said mixture 15'GM having a height less than a first predefined threshold value.

[0078] Figure 5 illustrates an advantageous embodiment of a method 200 according to the invention, particularly when the maxima(s) of a color profile are not extremely pronounced or significant with respect to a residual color intensity, i.e., a non-zero RCI intensity described on average by the detection zone 13 in the absence of analyte or between two color profiles. Thus, in Figure 5, we find a first color profile 15', called the "control" profile, whose maxima 15'Ma, 15'Mb are intense (on the order of eight to twelve times the average residual RCI intensity), unlike the test or measurement color profile 15" whose maximum 15"M is weaker, i.e., The residual color intensity is on the order of one to two times the RCI residual color intensity. Such a residual intensity results from suboptimal capture conditions. Calculating the 115' color intensity as the area under the 100 curve for the 15'ra abscissa range is acceptable because it introduces a small approximation error, as the distribution of color intensities that characterizes it is much more significant than the RCI residual color intensity. On the other hand, performing such a calculation of the 115' color intensity for the second 15' color profile would lead to a significant approximation.To prevent such a drawback, substep 233 of calculating the intensity 115', 115" of colouring of an identified colouring profile includes a subtraction step from the area under the intensity curve 100 on said range of abscissas 15'ar, 15"ar determined characterizing a colouring profile 15', 15", of an area 15'ria, 15"ria of residual colouring intensities. Such an area 15'ria, 15”ria of residual colour intensities of a colour profile 15', 15” can consist of an area under a curve 101, 102 defined by an affine function linking the beginning 15'b, 15”b and the end 15'e, 15”e of the colour profile 15', 15”, on said range of abscissas 15'ar, 15”ar characterizing said colour profile 15', 15”. .

[0079] In this way, a method 200 according to the invention estimates more accurately the colour intensities I15i, in this case on the [Fig.5], the intensities 115' and 115”, of each colour profile 15i identified in substep 232, independently of the presence or not of a residual RCI colour intensity.

[0080] In the presence of a first 15' and a second 15" color profile identified in the working image 20s' which digitally transcribes the development zone 13 of a reactive strip 1, a method 200 according to the invention can implement a step 240 of producing a measurement M) of an analyte of interest from the respective color intensities 115', 115" of two color profiles 15', 15" expressed in a digital representation 20s' of the development zone 13 of said reactive strip 1.

[0081] According to a preferred embodiment, such a step 140 of producing a measurement M of an analyte of interest can result from calculating a ratio between the respective color intensities 115', 115" of two color profiles 15', 15". Thus, the presence of such an analyte is determined and measured as a percentage with respect to the reactivity potential of said test strip 1 expressed by the first color profile, referred to as the "control color profile". The higher said ratio between the color intensities 115' and 115", respectively of the control profile and the measurement profile 15", the more the analyte concentration is confirmed.

[0082] Quantification or measurement of the analyte of interest contained in the liquid biological sample received by the reagent strip 1 can be obtained in step 240 by comparing the ratio between the respective color intensities of the two profiles of color to predefined reference data. A comparison thus reflects the ratio of intensities to analyte concentration in the liquid biological sample received by the test strip 1. The reference data can be pre-established from the measurement of the analyte of interest at several concentrations in the liquid biological sample. Such reference data can be in the form of a calibration curve (concentration - ratio of intensities) associated with a test or a specific type TI of test strip, for example, determined in an optional substep 223 of a process 200 according to the invention.

[0083] A mobile terminal 2 can therefore deliver said measurement M via its output human-machine interface 25 to the user U. For this to happen, it is sufficient that said mobile terminal 2 has been previously adapted, by prior installation in program memory 23, of a computer program product whose execution of program instructions by the processing unit 21 of the latter triggers the implementation of a measurement method 200 according to the invention. For this purpose, step 240 of a method 200 according to the invention can cause the output of said measurement M of an analyte of interest via the output human-machine interface 25 of the mobile terminal 2 as soon as it is produced.The user U of such a mobile terminal 2 thus has on the fly, i.e. in near real time, after a digital representation 20s of the reactive strip 1 has been captured in a step 210 of said process 200 by the image sensor 22 of his mobile terminal 2, then selected and a measurement M of the concentration of an analyte of interest has been produced in step 240 of such a process from respective colour intensities of at least two colour profiles identified in a step 230 by automatically exploiting a colour distribution expressed in a working image 20s' produced in a step 220.As an alternative or in addition to such a display, or more generally such direct feedback to the user U, said step 240 of a method 200 according to the invention may cause the measurement M and / or the ratio of color intensities, or even the color intensities of the identified profiles, to be recorded in the data memory 24 of the mobile terminal 2. Such a step 240 may also, or alternatively, cause the measurement to be transmitted to a remote application server 3 via communication means 26 of said mobile terminal 2.

Claims

1. Demands A method for the quantitative measurement of an analyte of interest by chromatography, said method being designed to be implemented by a processing unit (21) of a terminal (2) comprising an image sensor (22) and an output human-machine interface (25), said method (200) comprising: - a step (230) of producing a colour intensity (I15i, 115', 115”) for each colour profile (15', 15”) expressed in a digital representation (20s') of a development zone (13) of a reactive strip (1); - a step (240) of producing a measurement (M) of an analyte of interest from the respective color intensities (115', 115”) of two color profiles (15', 15”) expressed in said digital representation (20s') of the development zone (13) of said reactive strip (1); said process (200) being characterized in that: - said process (200) comprises: (i) a step (210) of acquiring a stream of digital representations (20i) of the reactive strip (1) delivered by the image sensor (22) and of selecting on the fly one of said digital representations (20i) as soon as it satisfies a set of predetermined relevance criteria; ii) a step (220) of developing a working image (20s') from said selected digital representation (20s), said working image describing a distribution of colour intensities (100) of said development zone (13) of said reactive strip (1); - the digital representation (20s') of a development area (13) of a reactive strip (1) used by the production step (230) of a colour intensity (115i, 115', 115”) for each colour profile (15', 15”) consists of the working image (20s'), said production step (230) being arranged to, from said distribution of colour intensities expressed by said working image: i) identify each color profile (15', 15"); ii) calculate the color intensity of the latter; - the step (140) of producing a measurement (M) of an analyte of interest: i) consists of calculating a ratio between the respective colour intensities (115', 115”) of two colour profiles (15', 15”); ii) causes an output of said measurement (M) of an analyte of interest produced by the output human-machine interface (25) of the terminal (2).

2. A method (200) according to the preceding claim, wherein the step (210) of acquiring a stream of digital representations (20i) of the reactive strip (1) delivered by the image sensor (22) and of selecting, on the fly, one of said digital representations (20i) comprises: - a substep of capturing (201) a digital representation (20i); - a substep (203) of searching within said digital representation (20i) for a contour of an interior surface (12) of a reactive strip (1) comprising a revealing area (13), and of selecting said digital representation (20i): i) if a surface contour (12) describing a contour of a predefined geometric shape of reactive strip surface (1) has been identified, and ii) if a ratio between the area captured by such a surface contour (12) and the total area of ​​said digital representation (20i) is greater than and at a predetermined threshold.

3. A method according to the preceding claim, wherein the step (210) of acquiring a stream of digital representations (20i) of the reactive strip (1) delivered by the image sensor (22) and of selecting, on the fly, one of said digital representations (20i) comprises a substep of displaying it by the output human-machine interface (25) of the terminal (2) such that a suitable geometric shape describing a typical template of a "control" reactive strip is superimposed transparently on said digital representation (20i) in order to induce the user (U) of the terminal (2) to position the image sensor (22) of the terminal (2) relative to the reactive strip (1) so that said suitable geometric shape covers the visible surface of the reactive strip (1) on said digital representation (20i) displayed by said output human-machine interface.

4. A method (200) according to any one of the preceding claims, wherein the step (220) of developing an image of work (20s) from said selected digital representation (20s) includes: - a sub-step (221) of production of the working image (20s') consisting of: i) a discrimination of pixels describing a region of interest within the selected digital representation (20s), said region of interest expressing the area of ​​revelation (13); ii) a production of said working image (20s') comprising pixels expressing the respective light intensities of the pixels expressing the revelation area (13) in the selected digital representation (20s); - a substep (222) of correcting geometric distortions in the selected digital representation (20s) or in the working image (20s') produced with regard to an expected and predefined shape of a typical development area (13) of a reactive strip (1).

5. A method (200) according to any one of the preceding claims, wherein the step (230) of producing a color intensity (115i, 115', 115”) for each color profile (15', 15”) comprises: - a substep (231) of modeling the distribution of colour intensities expressed in the working image (20s') in the form of a colour intensity curve (100) describing the cumulative colour intensity by each set of pixels aligned perpendicularly to a longitudinal axis (AL) of the revelation area (13); - a substep (232) of identifying a color profile (15', 15”) from said color intensity curve and determining a range of abscissas (15'ar, 15”ar) characterizing the beginning (15'b, 15”b) and the end (15'e, 15”e) of said color profile (15', 15”); - a substep (233) of calculating the colour intensity of said colour profile identified (15', 15”) as being the area under the intensity curve (100) on said range of abscissas (15'ar, 15”ar) determined.

6. A method (200) according to the preceding claim, wherein an instance of the substep (232) of identifying a color profile (15', 15") from said color intensity curve and determination of a range of abscissas (15'ar, 15”ar) characterizing the beginning (15'b, 15”b) and the end (15'e, 15”e) of said colour profile (15', 15”), and an instance of the substep (233) of calculating the colour intensity of said identified colour profile are iterated (234) from the lowest abscissa to the highest abscissa of said colour intensity curve (100).

7. A method (200) according to any one of claims 5 and 6, wherein the substep (233) of calculating the intensity (115', 115”) of colouring of said identified colouring profile comprises a subtraction step from the area under the intensity curve (100) on said determined abscissa range (15'ar, 15”ar) characterizing a colouring profile, of an area (15'ria, 15”ria) of residual colouring intensities.

8. Method (200) according to claim 7, wherein the area (15'ria, 15”ria) of residual colour intensities of a colour profile (15', 15”) consists of the area under a curve (101, 102) defined by an affine function linking the beginning (15'b, 15”b) and the end (15'e, 15”e) of the colour profile (15', 15”) on said range of abscissas (15'ar, 15”ar) characterizing said colour profile (15', 15”).

9. Product computer program (P) comprising program instructions which, when written into a program memory (23) of a terminal (2) further comprising a processing unit (21), an output human-machine interface (25) and a data memory (24), and interpreted or executed by said processing unit (21) of the latter (2), cause the implementation of a method (200) according to any one of claims 1 to R

10. 1 a O. Mobile terminal (2) comprising a program memory (23), a processing unit (21), an output human-machine interface (25) and a data memory (24), characterized in that the program memory (23) contains the program instructions of a computer program product according to claim 9.

Images